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Exhibit 4.20  


  
 

    IRREVOCABLE CONVERSION NOTICE AND AGREEMENT    
    


	To:
	Pioneer
Drilling Company ("Pioneer")

9310 Broadway, Building I

San Antonio, Texas 78217 



        The
undersigned registered holder of an original aggregate principal amount of $27,000,000 of Pioneer's 6.75% Convertible Subordinated Debentures due July 3, 2007, (the
"Debentures"), hereby exercises its option to convert the Debentures into 6,264,501 shares of common stock of Pioneer in accordance with the terms of the Debenture Agreement by and between WEDGE
Energy Services, L.L.C. ("WEDGE") and Pioneer dated as of July 3, 2002, as amended (the "Debenture Agreement"), effective immediately prior to the closing of the Offering (defined below) and
subject to the provisions of the last two paragraphs hereof, and directs that the shares issuable and deliverable upon such conversion, together with any check for cash deliverable upon such
conversion, be issued and delivered to WEDGE at the following address: 


WEDGE
Energy Services, L.L.C.

1415 Louisiana, Suite 3000

Houston, Texas 77002 


        This
notice shall be deemed to be an irrevocable exercise of the option to convert the Debentures immediately prior to the closing of the Offering (the "Effective Time"); provided that,
this notice shall become revocable upon written notice to Pioneer if the closing of the Offering has not occurred prior to December 31, 2004. WEDGE covenants and agrees to deliver the
Debentures to Pioneer within 5 days of the date of this notice. Pioneer covenants and agrees that after such time as Pioneer has received the Debentures and until the earlier of (i) the
Effective Time or (ii) such time as WEDGE is entitled to revoke and does revoke this notice pursuant to the first sentence of this paragraph, Pioneer shall hold the Debentures in escrow, after
which, in the case of a revocation, Pioneer shall return the Debentures to WEDGE upon WEDGE's written request. Unless notice has been earlier revoked
pursuant to the first sentence of this paragraph, at the Effective Time, the Debentures will be converted into 6,264,501 shares of Pioneer common stock. 


        For
purposes of this notice, the term "Offering" shall mean the offering which is contemplated to be made by Pioneer and certain selling shareholders, including WEDGE, pursuant to a
registration statement on Form S-1 with the U.S. Securities and Exchange Commission to be initially filed in the quarter ending September 30, 2004 and pursuant to which
Pioneer is proposing to offer up to 4,600,000 shares of its common stock in a public offering and certain selling shareholders, including WEDGE, are also proposing to offer up to 5,269,320 shares of
Pioneer's common stock which they hold. This notice shall not affect Pioneer's right to redeem the Debentures in accordance with the terms of the Debenture Agreement and the parties hereto agree that,
notwithstanding any provision in the Debenture Agreement to the contrary regarding the effective date of the conversion, this notice shall constitute a valid 








exercise
of WEDGE's conversion rights under the Debenture Agreement effective as of the Effective Time. 



	

July 9, 2004	

WEDGE Energy Services, L.L.C.
	

 	

By:	

/s/  RICK E. BLOHM      

	 	Title:	Vice President






Accepted and Agreed to July 9, 2004: 



	

/s/  WM. STACY LOCKE      
 Wm. Stacy Locke

President and Chief Executive Officer

Pioneer Drilling Company	
 	

 













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IRREVOCABLE CONVERSION NOTICE AND AGREEMENT